Elevated from the comments:
In 1941, Muslim League passed a resolution making an oath of allegiance to Pakistan as a condition for Muslim League membership.
Muslim League proceedings quoted from Foundations of Pakistan, All-India Muslim League Documents: 1906-1947, Syed Sharifuddin Pirzada, Vol II 1924-1947, Metropolitan Book Co, New Delhi.
All India Muslim League Twenty-Eighth Session, Madras, April 1941
Moving Resolution II on the amendment to the Constitution[of the Muslim League], Nawabzada Liaquat Ali Khan said: We are altering our creed to-day and bringing it into line with the Lahore Resolution, popularly known as Pakistan. Our experience has convinced us that one Federation for the whole of India would create chaos, is impracticable and would lead to the domination of one community over the rest of India. It would never be acceptable to the Muslims.
He declared that Pakistan had become their article of faith, and amendment now before the House would be an effective reply to those who had alleged that it was merely a counter for bargaining. Another implication of the amendment was that every Muslim who was to join the League from now onwards would have to take an oath of allegiance to Pakistan.
Explaining the amendment, he said that the safeguards for the non-Muslims in Pakistan would be framed in consultation with the minorities and would not be imposed on them. It should be evident, he said, that our aim and object is to do justice to all. "Those who want India to be free should accept Pakistan, which will lead to the freedom of all", he added. The amendment was supported by speakers in English, Urdu and Tamil.